Drop background color optimization for composited layers

LayoutTests/compositing/rtl/rtl-fixed-overflow-expected.txt

Index: LayoutTests/compositing/rtl/rtl-fixed-overflow-expected.txt
diff --git a/LayoutTests/compositing/rtl/rtl-fixed-overflow-expected.txt b/LayoutTests/compositing/rtl/rtl-fixed-overflow-expected.txt
index 3b58957fc8c3fabb5814cf2525488b19da3631c2..d03e5d4dd957049d505d1ede4b09887ef4f5ce4b 100644
--- a/LayoutTests/compositing/rtl/rtl-fixed-overflow-expected.txt
+++ b/LayoutTests/compositing/rtl/rtl-fixed-overflow-expected.txt
@@ -11,6 +11,8 @@
           (position 265.00 50.00)
           (bounds 100.00 100.00)
           (contentsOpaque 1)
+          (drawsContent 1)
+          (backgroundColor #008000)
         )
       )
     )